Your post is unclear. Do you mean the speaker level input and output on the sub, or a line level input and output on the sub? Which are you currently using?
If you use the tape monitor to output to the subwoofer, the volume control will not affect the level of the subwoofer, so you don't want to do it that way. You will not get sound from the subwoofer by hooking it up to inputs (like the phono or CD inputs) on the receiver. You have to hook it up to some sort of output on the receiver for the signal to go out from the receiver. Inputs are for inputting signals, outputs are for outputting signals. That is why they are called what they are called.
